Assessment the watershed management measures role in evapotranspiration processes in paired watersheds of Taleghan

On average, 70 percent of the precipitation that reach Earth's surface, returns to the atmosphere through evapotranspiration, and this rate reaches 90 percent in arid areas. Meanwhile, watershed measures directly related to water, soil and plant, and ultimately to evapotranspiration on the natural resources region (ecochydrology). In this study, in order to study the effect of biological activities of watersheds (enhancement and increase of vegetation) on the process of soil moisture and evapotranspiration changes, paired watersheds of Taleghan, Alborz Province were selected. In order to calculate evapotranspiration by soil moisture balance method, soil moisture monitoring points were selected using field and laboratory studies in three main areas (northwest, eastern and southeast) and three replications and at three depths of 0-20, 40-20 and 40 -60 cm during plant growth period in 2017. Data were analyzed by ANOVA method, and Duncan test. The results showed that the actual evapotranspiration in the treated watershed and control watersheds were not statistically significant and, respectively, they showed 181 mm and 159 mm in a period of growth. In other words, the actual evapotranspiration value in the treated watershed was 14% higher than the control one during the growth period. Also, the results showed that evapotranspiration under different aspect slopes had a significant difference. The total actual evapotranspiration in the northwestern slopes were 229 and 226 mm, in east slopes were 207 and 171 and in the southeastern slopes were 109 and 80 mm in the treated and control watersheds, respectively.